Scaffold unit

ABSTRACT

An extendible scaffold unit comprises at least two support platforms or two support frames ( 12, 14, 16 ), at least one of the support platforms or support frames ( 12, 14, 16 ) being movable between a lowered position and a raised position, a plurality of scissor linkages ( 35, 36, 37 ) linking one support platform or support frame ( 12, 14, 16 ) with a next support platform or support frame ( 12, 14, 16 ), each of the scissor linkages ( 35, 36, 37 ) including a plurality of legs ( 26, 28, 30, 32 ), each scissor linkage having a leg pivotally connected to or near a corner of one of the support platforms or support frames and a leg pivotally connected to or near a corner of a next support platform support frame, wherein a leg is pivotally connected at or near each corner of a support platform or support frame. By providing a leg pivotally connected at or near each corner of a support platform or support frame, the support platform or support frame is supported at or near each corner when in the raised position. This provides a stronger, more stable and more secure support to the platform/frame.

TECHNICAL FIELD

The present invention relates to a scaffold unit. More particularly, thepresent invention relates to a scaffold unit that can be moved from alowered or retracted configuration to a raised or expandedconfiguration.

BACKGROUND ART

Scaffolding is widely used in the building and construction industries.Conventional scaffolding is erected from a number of separatecomponents. Typically, a number of posts or rods are fastened togetherusing brackets and bolts to form the scaffolding framework, with supportboards or planks being placed on the scaffolding framework to formwalkways or work platforms. Erection of conventional scaffoldingrequires that all of the components be delivered to a building site. Ascaffolding crew will then erect the scaffold. This can betime-consuming and can add to the cost of construction.

Some effort has been made in the past to develop scaffold units in whichthe work platforms can be moved between a lowered position and a raisedposition. For example, in U.S. Pat. No. 3,877,543, a scaffold unit isdescribed which includes a horizontal platform being mounted to aplurality of vertical posts so as to be vertically movable up-and-downalong the vertical posts. Rollers and drive rollers are pivotallymounted on an arm lever provided on the platform. A worm gear is coupledto the drive rollers to move the horizontal platform up and down thevertical posts by rotating the drive rollers. When a downward load isapplied to the platform, the rollers and drive rollers are automaticallypressed against the vertical posts so that the platform is preventedfrom slipping by the frictional force that is so generated. Productsknown as “mast climbers” have some similarity to the operating principleof the product disclosed in U.S. Pat. No. 3,877,543.

British patent number 191108619, which was filed in 1911, describes ascaffold unit in which support platforms can be raised and lowered toany desired level. This unit includes a plurality of support platformsthat are connected together by a series of articulated levers known as“lazy tongs.” The platform with the series of articulated levers restson an undercarriage mounted two wheels so that it can be easily moved toa desired location. In use, a shaft is turned to drive the articulatedlevers to a raised configuration. In the raised configuration,articulated levers are located below two corners of one end of eachsupport platform. Further articulated levers are located belowapproximate midpoint of each support platform and the support platformseffectively cantilever outwardly from these articulated levers.

GB 759187 describes a mobile working platform in which the platform issupported by extensible lattice members that are raised by hydraulic orother means from a mobile trolley or truck. In this British patent, asingle working platform is moved from a lowered position to a raisedposition by operating hydraulic rams to extend a pair of scissor armsthat are mounted on either side of a chassis and the platform. A rackand pawl mechanism locks the platform into place.

GB 2022672 describes extensible scaffolding that uses a lazy tongsarrangement. Each of the lazy tongs arrangement comprises two pairs oflevers. The levers of each pair cross each other and are pivotallyconnected together where they cross. A plurality of transversestructural members extend at right angles to the lengthwise dimension ofthe lazy tongs arrangement, with each transverse member having two guideelements mounted for guided movement along the transverse member. Eachlever of the lazy tongs arrangement has a guide member attached at itsends. Two vertical scaffolding tubes extend in the same plane as thelazy tongs arrangement. To enable the lazy tongs arrangement to beextended, the lowermost of the transversely extending members carries agearbox carrying journals for to screw threaded shafts extendingparallel to the lowermost transverse member. Operation of this enablesthe guide members on the lowermost transverse member to move towardseach other to extend the lazy tongs arrangements and raise theextensible scaffolding. As the lazy tongs arrangements extend, therespective transverse members are raised and slide upwardly along thevertical members located at either end of the transverse members. Whenthe upper end of the structure reaches the required height, clampingbolts on the bottom transverse member are tightened to fasten the endsto the vertical scaffolding tubes. Then standing on the bottom member,the operator can tighten the bolts of the next member, and so forth,thereby allowing the operator to climb the scaffold and tighten thebolts. When in the extended position, the levers of the lazy tongsarrangements extend at an angle of between 20° and 30° to horizontal.

U.S. Pat. No. 3,820,631 describes a platform lift device which issuitable for raising workmen and equipment to elevated positions whichwill enable them to perform maintenance work on aircraft. This patentdescribes existing lifting mechanisms that use conventional scissormechanisms to raise and lower the work platforms. This patent statesthat such conventional scissor mechanisms possess at least threeinherent disadvantages when employed as a lifting mechanism. Onedisadvantage is the fact that the effective supported base area definedby the scissor ends decreases as the platform is raised, resulting inprogressively less stability at higher elevations. The seconddisadvantage is the fact that the beams which comprise such a scissorlinkage are subjected to bending loads and must therefore be relativelystiff to support loads. A third disadvantage is that the scissorlinkages must be relatively long to accomplish high lift operations ifdone in one stage. Such long linkages necessitate a large and cumbersomestorage pedestal chassis. In order to overcome these disadvantages, thelift platform of this patent has an elevating mechanism in whicheffectively the scissor lift arms of conventional scissor liftmechanisms are replaced with fluid power cylinders each having a ram orpiston mounted to them so that struts that are pivotally connected tothe chassis and the lift platform extend relative to the fluid powercylinders to thereby raise the work platforms. A mechanical interlock isused to ensure that the fluid power cylinders each extend atsubstantially identical values of incremental movement even if theplatform is unequally loaded.

U.S. Pat. No. 4,088,203 describes an adjustable scaffold comprising aplatform on base and an adjustable interconnecting support structure.The adjustable interconnecting support structure comprises a number ofsets of scissor mechanisms. Lifting means, typically hydraulic cylinderswith lever brackets and support brackets pivotally attached thereto, arepositioned between sets of scissor connectors, rather than within them.In other words, each cylinder is attached to cross members fromdifferent sets of scissor connectors. This is stated to provide a sturdyand safe lifting mechanism is capable of lifting substantial loads ofpersonnel and equipment. A pair of scissor mechanisms are attached tothe platform.

It will be clearly understood that, if a prior art publication isreferred to herein, this reference does not constitute an admission thatthe publication forms part of the common general knowledge in the art inAustralia or in any other country.

SUMMARY OF INVENTION

The present invention is directed to a scaffold unit which may at leastpartially overcome at least one of the abovementioned disadvantages orprovide the consumer with a useful or commercial choice.

With the foregoing in view, the present invention in one form, residesbroadly in a scaffold unit comprising at least two support platforms ortwo support frames, at least one of the support platforms or supportframes being movable between a lowered position and a raised position, aplurality of scissor linkages linking one support platform or supportframe with a next support platform or support frame, each of the scissorlinkages including a plurality of legs, each scissor linkage having aleg pivotally connected to or near a corner of one of the supportplatforms or support frames and a leg pivotally connected to or near acorner of a next support platform support frame, wherein a leg ispivotally connected at or near each corner of a support platform orsupport frame.

By providing a leg pivotally connected at or near each corner of asupport platform or support frame, the support platform or support frameis supported at or near each corner when in the raised position. Thisprovides a stronger, more stable and more secure support to theplatform/frame.

In one embodiment, the scaffold unit further comprises a drive means forraising and lowering at least one of the support platforms or supportframes between the lowered position and the raised position.

The drive means is suitably mounted to the scaffold unit. This allowsthe drive means to raise and lower the support platforms withoutrequiring an externally provided drive system.

In a second aspect, the present invention provides a scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, a plurality of legsextending between one support platform or support frame and a nextsupport platform or support frame, at least some of the legs having apivotal connection to the support platform or support frame, the legsbeing movable during movement of the scaffold unit from the loweredposition to the raised position and vice versa, the legs extending at anangle of less then 10° to horizontal when the scaffold unit is in thelowered position.

In one embodiment, at least some of the legs have a pivotal connectionat or near corners of the support platform or support frame.

Suitably, the support platforms or support frames that move duringraising or lowering of the scaffold unit move in an essentially verticaldirection during raising or lowering. By this, it is meant that thesupport platforms or support frames have a negligible horizontalcomponent to their movement during raising and lowering of the scaffoldunit.

The scaffold unit may further comprise a drive means for causing atleast some of the legs to pivot about their pivotal connection at ornear the corners of the support platform or support frame during raisingand lowering of the scaffold unit.

In some embodiments, the legs extend at an angle of less than 8° tohorizontal when the scaffold unit is in the lowered position. In otherembodiments, the legs extend at an angle of from 3° to 7° to thehorizontal when the scaffold unit is on the lowered position. In furtherembodiments, the legs extend at an angle of from 4° to 6°, or even at anangle of about 4° to 5°, to the horizontal, when the scaffold unit is inthe lowered position.

The scaffold unit may further comprise a further drive means tofacilitate initial movement of a support platform or support frame froma lowered position. The further drive means may be selected from one ormore of a column lifter, a hydraulic ram, an air bag, a pneumaticcylinder or a biasing means. In one embodiment, the further drive meanscomprises a biasing means that provides a biasing force to the legs whenthe scaffold unit is in the lowered position, the biasing force actingin a direction to assist raising the scaffold unit. In this manner, whenthe drive means is energised or actuated to raise the scaffold unit froma lowered position, the biasing means assists in raising the legs byapplying an additional biasing force to the legs during the initialmovement of the legs from the lowered position. This facilitates theinitial movement of the legs from the lowered position (at which thelegs are at an almost horizontal orientation) to the raised position.Further, a smaller or lower powered drive means may be used to raise thelegs from the lowered position.

The biasing means may comprise one or more springs, or one or moreresilient members, or one or more elastomeric or rubber members, or oneor more elastomeric or rubber blocks, or one or more struts, such as oneor more gas struts. The one or more springs, one or more resilientmembers, one more elastomeric or rubber members or one or moreelastomeric or rubber blocks or one or more struts may extend in avertical direction. In other embodiments, they may extend in ahorizontal direction, or indeed they may extend at any direction thatcan be used to assist the initial movement from the lowered position.

In some embodiments, the further drive means contacts one support frameor support platform and another support frame or support platform whenin the lowered position, but the further drive means only contacts theone support frame or support platform when in the raised position.

In some embodiments, the legs extend at an angle of greater than 80°, orgreater than 85°, to the horizontal when the scaffold unit is in theraised position. In some embodiments, the legs may extend at an angle ofabout 86.5° to the horizontal when in the raised position.

In the second aspect of the present invention, the links that arepivotally connected to the support platforms or support frames may formpart of scissor linkages.

In embodiments where the scaffold unit includes scissor linkages, thescissor linkages may comprise a first leg and a second leg, with thefirst leg being pivotally connected to a lower support platform orsupport frame at or near a corner of the lower support platform orsupport frame, the first leg and second leg being pivotally connected toeach other at an approximate midpoint thereof, the second leg having alower end that is reciprocally movable relative to the lower supportplatform or support frame, the first leg having an upper end that isreciprocally movable relative to an upper support platform or supportframe, the second leg having an upper end that is pivotally connected tothe upper support platform or support frame at or near a corner of theupper support platform or support frame.

In another embodiment, the scissor linkages may comprise a first leg anda second leg, with the first leg being pivotally connected to a lowersupport platform or support frame at or near a corner of the lowersupport platform or support frame, the first leg and the second legbeing pivotally connected to each other at an approximate midpointthereof, the second leg having a lower end that is reciprocally movablerelative to the lower support platform or support frame, a third leghaving an upper end that is pivotally connected to an upper supportplatform or support frame at or near a corner of the upper supportplatform or support frame, a fourth leg having an upper end that isreciprocally movable relative to the upper support platform or supportframe, the third leg and the fourth leg being pivotally connected toeach other at an approximate midpoint thereof, the third leg having alower end that is pivotally connected to an upper end of the first legand the fourth leg having a lower end that is pivotally connected to anupper end of the second leg.

The legs that are reciprocally movable relative to one of the supportplatforms or support frames may suitably be connected to one or morerollers that can move along a track or guide in or mounted to thesupport platform or support frame.

It will be understood that as the legs that are reciprocally movablerelative to one of the support platforms or support frames are moved,those legs will also rotate or pivot relative to the support platform orsupport frame.

In some embodiments, the pivotal connection points of the respectivelegs to one of the platforms or support frames are located outwardly ofthe sliding ends of the other legs of each scissor linkage. This is apreferred embodiment. In another embodiment, the sliding ends of therespective scissor linkages are located outwardly of the pivotalconnection points of the other ends of each scissor linkage.

In embodiments where scissor linkages are used to link a lower supportplatform or support frame to an upper support platform or support frame,it is preferred that the legs of the scissor linkages extend at an angleof at least 80°, or at least 85°, to the horizontal when the scaffoldunit is in the raised position.

In some embodiments, the scaffold unit is fitted with a drive means toraise and lower the unit. The drive means may comprise a drive motor,such as an electric motor. The electric motor may cause a drive bar ordrive member to reciprocally move relative to one of the supportplatforms or support frames, movement of the drive bar or drive membercausing the legs to move. The scaffold unit of the present invention maydesirably have the drive means mounted on board.

In some embodiments, the scaffold unit may also be provided with abraking means that can be selectively actuated to prevent raising orlowering of the scaffold unit and selectively turned off or disengagedto allow raising or lowering of the scaffold unit. In some embodiments,the braking means may engage with one or more components of the drivemeans.

In other embodiments, the scaffold unit may be moved from a loweredposition to a raised position by suspending the scaffold unit from acrane, releasing a braking means or releasing a locking means to allowthe scaffold unit to expand under its own weight and subsequentlyengaging the braking means or locking means when the scaffold unit isfully raised. In a further alternative, the scaffold unit may be raisedand lowered by placing the scaffold unit on the ground (or on a supportbase), releasing a braking means or releasing a locking means, raisingthe scaffold unit to the raised position by use of a crane andre-engaging the braking means or the locking means to hold the scaffoldunit in the raised position. Lowering may be achieved by releasing thebraking means or locking means and lowering the crane to thereby lowerthe scaffold unit under its own weight.

In one embodiment, the scaffold unit is provided with scissor linkagesand the drive bar or drive member causes at least some of the legs thatare mounted for reciprocal movement relative to one of the supportplatforms or support frames to move relative to the support platform orsupport frame.

In one embodiment, the drive motor causes a ball screw or a worm gear torotate, the ball screw or worm gear extending through a nut fixedlymounted to a drive bar or drive member, wherein rotation of the ballscrew or worm gear causes the drive bar or drive member to movelaterally outwardly or laterally inwardly. The drive motor may passdrive through a gear arrangement to cause rotation of the ball screw orworm gear.

In some embodiments, the scissor linkages may be moved and repositionedinwardly or outwardly relative to the support frame or support platform.In one embodiment, the support frame or support platform is providedwith a plurality of spaced openings, one leg of a scissor linkage havingan opening that can be brought into alignment with one of the pluralityof spaced openings and a connecting pin passed through the alignedopenings to thereby pivotally connect the one leg of the scissor linkageto the support platform or support frame. It will be appreciated thatthe other leg of the scissor linkage that is associated with thatsupport platform or support frame can move along the support platform orsupport frame (for example, by use of appropriate rollers slides) andthis allows easy repositioning of the scissor linkage. To facilitaterepositioning, the drive means may be disconnected from the leg of thescissor linkage that can move along the support platform or supportframe. This may be achieved by use of an appropriate clutch mechanism inthe drive means, or use of an appropriate quick disconnect mechanism inthe drive means.

Accordingly, in a third aspect, the present invention provides ascaffold unit comprising at least two support platforms or two supportframes, at least one of the support platforms or support frames beingmovable between a lowered position and a raised position, a plurality oflegs extending between one support platform or support frame and a nextsupport platform or support frame, at least some of the legs having apivotal connection to the support platform or support frame, the legsbeing movable during movement of the scaffold unit from the loweredposition to the raised position and vice versa, wherein a position ofthe pivotal connection between a leg and the support platform or supportframe can be moved between a plurality of positions. In this aspect, aplurality of scissor linkages may extend between adjacent supportplatforms or support frames.

In a fourth aspect, the present invention provides a scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, at least one of thesupport platforms or support frames being provided with a supportsurface on which a worker can stand, the support surface including ahorizontal extension movable between a retracted position and anextended position, the horizontal extension extending outwardly from thesupport platform or support frame when extended.

In some embodiments, the horizontal extension extends along a length ofthe support platform or support frame. The horizontal extension mayextend towards a building located near or adjacent to the scaffold unit.In this manner, the scaffold unit can be spaced from the building tominimise the possibility of the scaffold unit coming into contact withthe building and damaging the building and the horizontal extensionbeing extended to provide a working platform that has an end locatedvery near or in contact with the building.

In some embodiments, the scaffold unit is provided with a protectivescreen on one side thereof. The protective screen may automaticallyextend when the scaffold unit is raised. The protective screen may bemade from a mesh material or a shade cloth material. The protectivescreen may be a removable screen.

The scaffold unit may also be provided with one or more handrails. Inuse when the scaffold unit is in the raised position, the handrails mayextend horizontally along at least an outer side of the scaffold unit.Additional handrails may be mounted to one or more ends of the scaffoldunit if the scaffold unit itself comprises an end of a scaffoldinginstallation. The handrails may be removably mounted to the scaffoldunit.

In one embodiment, the uppermost support platform or support frame maybe provided with one or more handrails or guardrails that are removablymounted to a scaffold unit.

The support platform or support frame may have a support surface thatenables a worker to stand or walk thereon.

The scaffold unit may also be provided with one or more stays extendingbetween one support platform or support frame and a next supportplatform or support frame. The one or more stays may extend diagonallybetween the support platforms or support frames. The one or more staysmay be extendable stays, such as telescoping stays. The one or morestays may provide additional resistance to movement of the supportplatforms or support frames when in the raised position. The one or morestays may include self locking means to lock the stays into an extendedposition when the scaffold unit is moved to the raised position.

The scaffold unit may be arranged such that a further scaffold unit canbe located on top if access to a higher level is required. The scaffoldunit may be provided with locking means for locking a first scaffoldunit to a second scaffold unit positioned on top of the first scaffoldunit. The locking means may comprise a locking bar extending throughapertures located in the first scaffold unit and the second scaffoldunit. The apertures may comprise aligned apertures. The locking bar mayprevent relative horizontal movement and vertical movement between thefirst scaffold unit and the second scaffold unit.

The scaffold unit may be provided with a base unit. The base unit maycomprise a separate unit upon which the scaffold unit is supportedand/or connected. In one embodiment, the base unit may comprise a frame.The frame may have one or more support surfaces on which the scaffoldunit may be supported. The frame may include a plurality of legs movablebetween a retracted position and an outward position. The plurality oflegs may comprise adjustable legs. The base unit allows for convenientsetup of the scaffold unit. In particular, the base unit may be locatedat the desired position at which the scaffold unit is to be located. Thelegs may be moved to the outward position and the height of the legsadjusted to account for any unevenness in the ground and to set the baseunit at the correct height. A scaffold unit may then be positioned onthe base unit.

In other embodiments, the scaffold unit may be provided with adjustablelegs or adjustable feet that extend below the lower support platform orsupport frame in use.

In another embodiment, the present invention provides a scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, a plurality of legsextending between one support platform or support frame and a nextsupport platform or support frame, the legs comprising telescopicallyextendable and telescopically retractable legs.

In one embodiment, the telescopic legs are raised and lowered by use ofhydraulic cylinders, pneumatic cylinders, or electric motors. In oneembodiment, the telescopic legs are raised and lowered by use of adriving means mounted on board the scaffold unit.

In a further aspect, the present invention provides a scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, a plurality of scissorlinkages linking one support platform or support frame with a nextsupport platform or support frame, each of the scissor linkagesincluding a plurality of legs, wherein the legs of the scissor linkagesextend at an angle of at least 80° to horizontal when the scaffold unitis in the raised position. In some embodiments, the scaffold unit has atleast 4 sets of scissor linkages linking one support platform or supportframe for next support platform or support frame.

In all embodiments of the present invention, the scaffold unit may beused in a manner that does not require the scaffold unit to be attachedto a building or other structure. In this regard, the scaffold unit canprovide a sufficiently stable base to enable the scaffold unit to standby itself next to a building.

The scaffold unit of the present invention provides a scaffold unit thatcan be expanded from a lowered position in which the scaffold unit has alow profile, compact configuration to a raised position in which thescaffold unit enables access to higher levels. In some embodiments, thescaffold unit comprises three support platforms or support frames, beinga lower support platform or support frame, an intermediate supportplatform or support frame and an upper support platform or supportframe. In one embodiment, the drive means may be mounted to theintermediate support platform or support frame. In other embodiments,the drive means may be mounted to the lower support platform or supportframe, or the drive means may be mounted to the upper support platformor support frame. In some embodiments, more than one support platform orsupport frame may be provided with drive means. The drive means may beeffective to raise and lower all of the support platforms or supportframes.

The scaffold unit of the present invention may further be provided withaccess stairs. The access stairs may allow access between supportplatforms or support frames on different levels. The scaffold unit maybe further provided with rubbish chutes. The rubbish chutes may beremovable rubbish chutes. The rubbish chutes may be attached to thescaffold unit when it is in the raised position and removed from thescaffold unit before it is moved back to the lowered position. Thescaffold unit may be further provided with loading bays.

The scaffold unit may be provided with a locking means to lock thescaffold unit in the lowered position. This can be useful fortransportation and storage of the scaffold unit.

Any of the features described herein can be combined in any combinationwith any one or more of the other features described herein within thescope of the invention.

The reference to any prior art in this specification is not, and shouldnot be taken as an acknowledgement or any form of suggestion that theprior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments of the invention will be described with reference tothe following drawings, in which:

FIG. 1 shows a perspective view of a scaffold unit in accordance with anembodiment of the present invention in a lowered position;

FIG. 2 shows a front view of the scaffold unit shown in FIG. 1;

FIG. 3 shows an end view of the scaffold unit shown in FIG. 1;

FIG. 4 shows a top view of the scaffold unit shown in FIG. 1;

FIG. 5 shows a perspective view of the scaffold unit shown in FIG. 1 ina partly raised state. In FIG. 5, the scaffold unit is approximatelyhalf extended;

FIG. 6 shows a front view of the scaffold unit shown in FIG. 5;

FIG. 7 shows an end view of the scaffold unit shown in FIG. 5;

FIG. 8 shows a perspective view of the scaffold unit of FIG. 1 in thefully raised position;

FIG. 9 shows a front view of the scaffold unit shown in FIG. 8;

FIG. 10 shows an end view of the scaffold unit shown in FIG. 8

FIG. 11 shows a front view that is generally similar to that shown inFIG. 6, but with a protective screen included;

FIG. 12 shows an end view of the scaffold unit shown in FIG. 11;

FIG. 13 shows a view similar to that shown in FIG. 3, with FIG. 13indicating section line K-K;

FIG. 14 is a view that is similar to that shown in FIG. 2 but showingthe region of detail H;

FIG. 15 shows a plan view taken along section line K-K shown in FIG. 13;

FIG. 16 is a front view, partly in cross-section, of detail H shown inFIG. 14;

FIG. 17 is a front view, partly in cross-section, of detail J shown inFIG. 11;

FIG. 18 is a front view that is generally similar to that shown in FIG.9;

FIG. 19 is an end view is generally similar to that shown in FIG. 10 butwith a protective screen included;

FIG. 20 is a detailed view of section A-A shown in FIG. 13;

FIG. 21 is a detailed view of section D-D shown in FIG. 18;

FIG. 22 is a detailed view of region L shown in FIG. 11;

FIG. 23 is a detailed view of region M shown in FIG. 18;

FIG. 24 is an end view of part of the scaffold unit as shown in FIG. 12,but in large-scale than shown in FIG. 12;

FIG. 25 is an enlarged view of detail T shown in FIG. 24;

FIG. 26 is an enlarged view of detail P shown in FIG. 19;

FIG. 27 shows an enlarged view of detail W shown in FIG. 19;

FIG. 28 is a front view of the detail shown in FIG. 27;

FIG. 29 is an end view of the lower two support frames of the scaffoldunit, showing some internal details;

FIG. 30 is an enlarged view of detail AC shown in FIG. 29;

FIG. 31 is an enlarged view of detail AD shown in FIG. 18;

FIG. 32 is a perspective view of a scaffold unit in the fully raisedposition;

FIG. 33 is an enlarged view of detail AH shown in FIG. 32 showing anexploded view of the removable handrail;

FIG. 34 is an end view of a support platform of the scaffold unit inaccordance with the present invention;

FIGS. 35 to 37 show various views of a horizontal extending supportplatform being extended from the support deck of the support platformshown in FIG. 34 to reach a fully extended position shown in FIG. 37;

FIG. 38 shows an end view of a lower scaffold unit in a raised positionhaving an upper scaffold unit in a lowered position being mountedthereto;

FIG. 39 is a similar view to that shown in FIG. 38 with the locking pinengaged to lock both scaffold units together;

FIG. 40 is a similar view to that shown in FIG. 39, but with thehandrails from the upper support platform or support frame of the lowerscaffold unit transferred to the upper support frame of the upperscaffold unit;

FIG. 41 shows the upper scaffold unit shown in FIG. 40 being partlyextended partly raised;

FIG. 42 shows an enlarged view of detail F shown in FIG. 38;

FIG. 43 shows an enlarged view of detail H shown in FIG. 39;

FIG. 44 shows an enlarged view of detail G shown in FIG. 41.

FIG. 45 shows a perspective view of a “goalpost” is used as a mainconnector between a scissor and a deck for all locations except wherethe drive frame is located;

FIG. 46 shows the goalpost of FIG. 45 in a partially disassembled state;

FIG. 47 shows the goalpost of FIG. 45 apart and in line for assembly

FIG. 48 shows a perspective view of a base unit suitable for use with ascaffold unit in accordance with the present invention;

FIG. 49 shows a plan view of the base unit shown in FIG. 48;

FIG. 50 shows a side view of the base unit shown in FIG. 48;

FIG. 51 shows an end view of the base unit shown in FIG. 48;

FIG. 52 shows a perspective view of the base unit shown in FIG. 48 withone set of legs extended;

FIG. 53 shows a perspective view of the base unit shown in FIG. 48 withtwo sets of legs extended;

FIG. 54 shows a perspective view of the base unit shown in FIG. 48 witha different set of legs extended;

FIG. 55 shows a cross section of the leg assembly used on the base unitshown in FIG. 48;

FIG. 56 shows a side view of another embodiment of the present inventionin a lowered position. In FIG. 56, the scaffold unit is provided with avertically extending initial lift device or further drive means;

FIG. 57 shows a side view of the scaffold unit shown in FIG. 56 in apartly raised position;

FIG. 58 shows a side view of the scaffold unit shown in FIG. 56 but withthe initial lift device removed from one end and the scissor linkageremoved from the other end, for clarity;

FIG. 59 shows the scaffold unit as shown in FIG. 58 in a partly extendedposition;

FIGS. 60 to 63 show various views of a scaffold unit in accordance withanother embodiment of the present invention in which the position of thescissor linkages may be moved inwardly and outwardly relative to theends of the scaffold unit. FIGS. 60 to 63 show the scissor linkagesbeing in various positions;

FIGS. 64 and 65 show a scaffold unit in accordance with anotherembodiment of the present invention, with the scaffold unit having itsfixed pivoting points at an inner part of the scissor linkages. FIG. 64shows a scaffold unit in a lowered position and FIG. 65 shows thescaffold unit in a partly raised position;

FIG. 66 shows a side view of a scaffold unit in accordance with anotherembodiment of the present invention. In FIG. 66, adjacent supportplatforms or support frames are connected by the telescoping members;

FIG. 67 shows the scaffold unit of FIG. 66 in a partly raised position;

FIGS. 68 and 69 show a detailed view of an alternative biasing meansthat is used to assist in initial raising of the scaffold unit. In FIG.68, the scaffold unit is shown in the retracted position and FIG. 69 thescaffold unit shown in a partly extended position;

FIG. 70 shows a view similar to that shown in FIG. 15, but with analternative drive arrangement;

FIG. 71 shows a perspective view of a scaffold unit in an expandedposition, with the scaffold unit having the alternative biasing meansshown in FIGS. 68 and 69;

FIG. 72 shows an expanded view of the connection between the legs of thescissor mechanism of the scaffold unit shown in FIG. 71; and

FIG. 73 shows a view similar to that shown in FIG. 30 but of a scaffoldunit in accordance with an alternative embodiment of the presentinvention. This displays an alternate connection configuration of thehandrail at the front and rear of the unit

DESCRIPTION OF EMBODIMENTS

Persons skilled in the art will appreciate that the drawings have beenprovided for the purposes of illustrating preferred embodiments of thepresent invention. Therefore, it will be understood that the presentinvention should not be considered to be limited solely to the featuresas shown in the attached drawings.

FIGS. 1 to 3 show various views of a scaffold unit in accordance with anembodiment of the present invention. The scaffold unit 10 shown in FIGS.1 to 3 is shown in the lowered position. The scaffold unit 10 can beexpanded from the position shown in FIGS. 1 to 3 to a raised position oran expanded position as shown in FIGS. 8 to 10. FIGS. 5 to 7 show thescaffold unit 10 in a partly raised position. It will be appreciatedthat the scaffold unit 10 can also be moved (or retracted or lowered)from the raised position shown in FIGS. 8 to 10 back to the loweredposition shown in FIGS. 1 to 3.

The scaffold unit 10 comprises three support frames 12, 14, 16. Supportframe 12 is the lowest support frame. Support frame 16 is the uppersupport frame. Support frame 14 is an intermediate support frame. Thesupport frames 12, 14, 16 each carry or support a platform, boards,planks or the like that enable a worker and/or equipment to be supportedor carried thereon.

The scaffold unit 10 also includes guardrails 18, 20 that are mounted tothe upper support frame 16. The guardrails 18, 20 will be described inmore detail hereunder.

Each of the support frames is connected to an immediately adjacent ornext support frame by use of a plurality of linkage arrangements. Eachlinkage arrangement includes legs that are pivotally connected at ornear corners of the support frame. In the embodiment shown in theattached drawings, the linkage arrangements comprise scissor linkages.

With reference to FIGS. 5 and 6, a first linkage arrangement, generallydenoted at 21, comprises leg 22 that has a lower end 23 that ispivotally connected at or near a corner 24 of support frame 12. Thelinkage arrangement 21 further includes a leg 26 that has a lower end 27that is mounted to support frame 12 such that the lower end can move ina reciprocal manner relative to the support frame 12. For example, thelower end 27 of leg 26 may be mounted to a roller or slide that movesalong a guide in support frame 12. Legs 22 and 26 are pivotallyconnected to each other at pivot connection 28. Pivot connection 28 islocated at the approximate midpoint of legs 22 and 26.

The first linkage arrangement 21 further includes another leg 30 that ispivotally connected at its lower end to the upper end of leg 26. Inparticular, legs 26 and 30 pivotally connected at pivot connection 31.The upper end of leg 30 is mounted to support frame 14 such that theupper end of leg 30 can move into reciprocal manner relative to thesupport frame 14. The linkage arrangement 21 further includes anotherleg 32 that is pivotally connected at its upper end to support frame 14at or near the corner 34 of support frame 14. Corner 34 of support frame14 is positioned vertically above corner 24 of support frame 12. Thelower end of leg 32 is pivotally connected at pivot connection 33 to theupper end of leg 21.

The lower support frame 12 and intermediate support frame are connectedby four similar linkage arrangements, generally denoted at 21, 35, 36and 37. Similarly, intermediate support frame 14 and upper support frame16 are connected by four similar linkage arrangements.

As can be seen from FIGS. 5 and 6, each of the linkage arrangements 21,35, 36, 37 has a leg that is pivotally connected at or near each cornerof support frame 12 and at or near each corner of support frame 14.

As the scaffold unit 10 is raised from the lowered position shown inFIGS. 1 to 3 to the raised position shown in FIGS. 8 to 10, the legs ofeach linkage arrangement adopt a more vertical configuration. Inparticular, in the lowered position shown in FIGS. 1 to 3, the legs ofthe linkage arrangements may extend at an angle of less than 10° to thehorizontal, particularly between four and 8° to the horizontal. Indeed,in the embodiment shown in the attached drawings, the legs of thelinkage arrangements extend at approximately 4.6° to the horizontal whenthe scaffold unit 10 is in the lowered position. When the scaffold unit10 is in the raised position as shown in FIGS. 8 to 10, the legs of thelinkage arrangements extend at an angle of greater than 80°, moresuitably at an angle greater than 85°, to the horizontal. Indeed, in theembodiment shown in the attached drawings, the legs of the linkagearrangements extend at an angle of 86.5° when the scaffold unit 10 is inthe raised position. As the legs of the linkage arrangements are almostvertical when the scaffold unit 10 is in the raised position, thelinkage arrangements can support significant weight. Further, the almostvertical linkage arrangements are located at or near each corner of therespective support platforms of the scaffold unit 10. This provides goodstability to the scaffold unit 10 when it is in the raised position.

Scaffold unit 10 may also be provided with diagonal stays 38, 40 thatextend from one corner of support frame 12 to a diagonal corner ofsupport frame 14. As best shown in FIGS. 5 and 8, the diagonal stays arelocated near one side of the scaffold unit 10. In this way, a more openspace is provided at the other side of the scaffold unit 10, in order toprovide a clear or more open space for workmen to access a building fromthe scaffold unit 10. The stays 38, 40 may comprise telescoping stays sothat the stays can expand or lengthen as the scaffold unit 10 is raisedand the stays can retract or shorten as a scaffold unit 10 is lowered.The stays 38, 40 are suitably pivotally mounted at their respective endsto the respective parts of the lower support frame 12 and intermediatesupport frame 14. Similar stays 42, 44 are provided between theintermediate support frame 14 and the upper support frame 16. The staysprovide additional rigidity to the scaffold unit 10 when it is in theexpanded position.

FIG. 12 shows a scaffold unit 10 that is fitted with a protective screen46. Protective screen 46 extends between the lower support frame 12 andthe intermediate support frame 14. Similarly, a protective screen 48extends between the intermediate support frame 14 and the upper supportframe 16. The protective screens 46, 48 may be made from a mesh materialor a shade cloth type material or indeed from any material known to besuitable for forming protective screens for use in scaffolding. Theprotective screen may be made from a single piece of material, or it maybe made from two pieces of material, or indeed it may be made from morethan two pieces of material. Protective screens 46, 48 are provided tominimise the risk of workmen dropping tools or other objects from thesupport platforms. They also provide enhanced protection against fallingfor workers working on the support platforms 12, 14. It will beappreciated that the scaffold unit 10 shown in FIG. 12 is only partlyraised. As a result, the protective screens 46, 48 shown in FIG. 12 havenot been pulled taut and they tend to bag as a result. Further detailsof the protective screens will be provided hereunder with reference toFIGS. 24 to 26.

FIG. 15 shows a top view of the intermediate support frame 14, but withthe support platform removed for greater clarity. The support frame 14comprises a plurality of frame members. In particular, the support frame14 includes end frame members 50, 52 and side frame members 54, 56. Theend frame members 50, 52 and the side frame members 54, 56 may be in theform of beams, such as steel beams or aluminium beams or indeed beamsmade from any other material having comparable strength to aluminium orsteel, including C-section beams, or they maybe in the form of hollowsection steel beams, such as rectangular hollow section (RHS) beams. Theside frame members 54, 56 may be C-section beams. The support frame 14is also provided with corner castings 58, 60, 62, 64. The corner castingis may be in the form of ISO compliant corner castings for shippingcontainers or similar in order to facilitate movement and transportationof the scaffold unit. The respective beams and corner castings arewelded together to form a strong rectangular frame. Alternatively, therespective beams and corner castings may be bolted together, rivetedtogether or joined using a combination of bolts and rivets. Otherfasteners or fastening systems known to the person skilled in the artmay also be used.

The frame includes intermediate frame members 66, 68. Intermediate framemembers 66, 68 extend between the side frame members 54, 56 and arewelded thereto. The intermediate frame members 66, 68 are used to formpart of a housing for an electric motor 70. Electric motor 70 has anoutput shaft (not shown) that is connected to a gearbox 72. The outputshaft from gearbox 72 connects to a T-gearbox 74. T-gearbox 74 is usedto rotate ball screws 76, 78. The distal ends of the ball screws 76, 78are retained in bearing housings 80, 82 which allow the ball screws 76,78 to rotate whilst also holding the ends of the ball screws in place.The bearing housings 80, 82 mounted to the intermediate frame 14.

The intermediate frame 14 also houses drive bars 84, 86. Drive bars maybe in the form of beams or RHS sections. Drive bar 84 has rollers 88, 90attached thereto. Similarly, drive bar 86 has rollers 89, 91 attachedthereto. The rollers 88, 90, 89, 91 are mounted to roll in the channelformed by the C-beam of side frame members 54, 56. The reciprocallymovable ends of the legs 30, 92 are also mounted to drive bar 84 (leg 92is part of the linkage extending between the intermediate support frame14 and the upper support frame 16. Leg 92 is also shown in FIG. 6).These legs are also mounted to another roller 94. Roller 94 also rollsin a guide channel formed by the C-beam of side frame member 56. Theother reciprocally movable legs of the linkage arrangements are alsomounted to the respective drive bars 84, 86 in a similar manner.

The drive bars 84, 86 include an aperture through which the respectiveball screws 76, 78 can pass. Ball screw nuts 96, 98 are affixed to thedrive bars such that the ball screw 76, 78 engage with the ball screwnuts 96, 98. In this manner, when the ball screws 76, 78 are caused torotate by operation of the electric motor 70, interaction between theball screws and their respective ball screw nuts causes the drive bars84, 86 to move along the ball screws 76, 78. Depending upon theoperation of the electric motor, this causes the drive bars 84, 86 tomove either outwardly or inwardly, thereby causing the scaffold unit 10to either raise or lower.

The legs 32, 93 that are pivotally connected at or near the corner 34 ofthe intermediate support frame 14 are also shown in FIG. 14. As can beseen, the outer ends of legs 32, 93 are mounted about a pivot pin 99which, in turn, is connected to a connecting bar 100. Connecting bar 100also carries a pivot pin 101 that is used to connect the similar pivotedlegs (not numbered in FIG. 14 for clarity purposes) on the other side ofthe support frame 14. Pivot pins 99, 101 are pivotally mounted to therespective side frame members 54, 56.

The arrangement shown in FIG. 15 advantageously allows a single drivemotor to raise or lower both intermediate support platform 14 and uppersupport platform 16. In particular, if the scaffold unit 10 is in itslowered position (as shown in FIG. 1) and the drive motor 70 isenergised to cause the drive bars 84, 86 to move outwardly, this causesthe reciprocally movable ends of legs 32 and 92 (and the other similarlyreciprocally movable ends of the legs of the other linkage arrangements)to move outwardly. As a result, the linkage arrangements between theintermediate support frame 14 and lower frame 12 start to extend.Similarly, and at the same time, the linkage arrangements between theintermediate support frame 14 and the upper support frame 16 are alsocaused to extend. This results in the spacing between the support frames12, 14 and 16 increasing as the scaffold unit is raised. This enables acompact and yet robust drive mechanism to be used to raise and lower thescaffold unit 10.

It will also be appreciated that the drive means may be arranged on thelower support platform or support frame or on the upper support platformor support frame. Indeed, drive means may be provided on two or more ofthe support platforms or support frames.

Although use of an electric motor 70 is preferred in order to raise andlower the scaffold unit, the electric motor may be replaced by any otherknown apparatus to cause rotation of the shaft. For example, theelectric motor may be replaced by a hand operated wheel, by a nut thatcan be caused to rotate by use of an appropriate rattle gun or electricdrill having a suitable socket connection, or indeed by any other knownsystem for causing rotation of a shaft. In embodiments where an electricmotor is used, the electric motor may be powered by an externalelectricity supply or it may be powered by an on-board battery supply.

In some embodiments, the scaffold unit may also be provided with abraking means that can be selectively actuated to prevent raising orlowering of the scaffold unit and selectively turned off to allowraising or lowering of the scaffold unit. The braking means may engagewith one or more components of the drive means.

It will also be understood that there may be a number of alternativedrive systems or drive arrangements that may be used in the scaffoldunit of the present invention. Indeed, the present invention encompassesany drive system or drive arrangement or drive means that allows thescaffold unit to be raised and lowered.

FIG. 16 shows an enlarged cross sectional view of detail H shown in FIG.14. In FIG. 16, the scaffold unit 10 is in the lowered position. Thereciprocally movable end of leg 92 that is mounted to roller 94 canclearly be seen. Similarly, the reciprocally movable end of leg 26 canbe clearly seen. These are mounted to roller 110 that is adapted to movealong a guide formed in a channel in a side of frame member of lowersupport frame 12. Leg 32 can also be seen. Similarly, the reciprocalmovable end of leg 108 can be seen. This leg is mounted to roller 112.Roller 112 is mounted so that it can move along a channel or guideformed in a side frame member of upper support frame 16. The otherlinkage arrangements are similarly arranged.

In order to assist in moving the legs of the linkage arrangements fromthe lowered position in which the legs extend in an almost horizontaldirection (in the embodiment shown in FIG. 16, the legs extend at anangle of 4.6° to horizontal), biasing means 114, 115, 116, 117 areprovided. Biasing means 114, 116 are shown in FIG. 16, with all biasingmeans 114, 115, 116 and 117 being shown in FIG. 15. The biasing meansmay be in the form of blocks of rubber or elastomer. In otherembodiments, the biasing means may comprise one or more springs. Whenthe scaffold unit 10 is in the lowered position as shown in FIG. 16, thedrive bars 84, 86 contact and compress the biasing means 114, 115, 116,117. When it is desired to raise the scaffold unit 10, the drive motor70 is operated and this applies a force to the drive bars 84, 86. As thedrive bars 84, 86 are also compressing the respective biasing means atthis stage, the biasing means also provide an additional force to assistin pushing outwardly on the drive bars 84, 86. Thus, the initial pushingforce provided to the drive bars by the drive motor is enhanced by thereactive force caused by compression of the biasing means by the drivebars. Thus, at the very beginning of outer travel of the drive bars 84,86, a force that is larger than the force provided by the drive motoralone is applied. This assists in moving the legs from their almosthorizontal configurations. As the drive bars move outwardly, the legsmove to a more vertical orientation. It has been found that once thedrive bars have been moved sufficiently outwardly to clear the biasingmeans, the legs have a sufficiently vertical orientation to allow thepower of the drive motor to continue raising the legs. Independentengineers who provided a confidential review of the drive system of thepresent invention commented that the legs would not be able to be liftedby the drive motor if the closed angle was less then 10.5°. The presentinventors have shown that this is not the case.

FIG. 17 shows an enlarged view of detail J shown in FIG. 11. This is aview that is similar to the view shown in FIG. 16, but with the scaffoldunit 10 being raised to about a halfway position. As can be seen fromFIG. 17, the drive bars 84, 86 are now clear of the biasing blocks 114,116. The more vertical position of legs 30 and 92 can also be seen.

FIG. 20 shows an enlarged view taken along section A-A and section B-Bof FIG. 12 and FIG. 21 shows an enlarged view taken along section C-Cand section D-D of FIG. 18. These figures show one embodiment by whichthe guardrail 18 may be mounted to the upper support frame 16. Theguardrail 18 includes a generally vertical extending post 120. A button122 is mounted to an upper part of the vertical post 120. Button 122operates a cable 124 that extends through vertical post 120. Cable 124passes over fixed cable guides 126, 128, 130. The lower end of cable 124is connected to a movable tongue 132. The movable tongue 132 is housedin a housing 134 at lower end of the post 120. Housing 134 may comprisethe vertically extending lower part 222 of the post 120 (see FIG. 38).Housing 134 is received in a sleeve or bracket 136 that is welded toside frame member 138 of the upper support frame 16. The sleeve orbracket 136 has an open bottom. The low section of housing 134 forms astop member 140.

In order to mount the guardrail 18 to the upper frame member 16, thebutton 122 is depressed, which causes tongue 132 to be retracted. Thisis shown in FIG. 20. The housing 134 is then inserted into the sleeve orbracket 136 until tongue 132 is positioned below the lower end of sleeveor bracket 136. The button 122 may then be released, which causes thetongue 132 to be released and to extend outwardly, as shown in FIG. 21.This results in the tongue 132 retaining the housing 134 (and thevertical post and also the guardrail 18) in the sleeve or bracket 136.In order to remove the guardrail 18 from the upper frame member 16, thebutton is pressed again, which retracts the tongue, thereby enabling theguardrail 18 to be lifted out of the sleeve 136. It will be appreciatedthat the tongue may be biased to the extended position by use of abiasing means 133. Biasing means 133 may comprise a rubber block or aspring.

It will also be appreciated that the guardrail 18 may be provided with anumber of vertical posts 120. A plurality of the vertical posts may beprovided with the locking means as described above. It will also beunderstood that the guardrail may be connected to the upper platform bya number of other mechanisms or connections. For example, the guardrail18 may be simply bolted to the upper platform. Alternatively, theguardrail 18 may be received in one or more openings or pockets thatpresent in the upper surface of the upper platform or support frame orthat are attached to the side of the upper platform or support frame.

FIGS. 22 and 23 show operation of the stays. Stay 38 comprises atelescopically extendable stay having a hollow portion 140 that cantelescopically receive rod 142. Rod 142 is pivotally connected at itsupper end 144 to intermediate support frame 14. Similarly, although notshown, the lower end of hollow portion 140 is pivotally connected to thelower support frame 12. As the scaffold unit 10 continues to be raisedfrom the part raised position shown in FIG. 22 to the fully raisedposition shown in FIG. 23, the rod 142 continues to extend outwardlyfrom hollow portion 140 until the scaffold unit 10 reaches the fullyraised position. The stay 38 may be provided with a self lockingmechanism such that when the stay 38 is fully extended, the rod 142automatically locks in position relative to the hollow portion 140. Thestays result in increasing the rigidity of the scaffold unit 10 when inthe raised position.

FIGS. 24 to 26 show various views of one way of ensuring that theprotective screen 46 can be guided and retained in position. In FIG. 24,the scaffold unit 10 is partly raised, as shown in FIG. 6. A hand rail150 is mounted at the pivot points where the upper and lower legs of thelinkage 35 are pivotally connected to each other. The protective screen46 may be in the form of a fabric or mesh (such as a shade cloth typemesh) and it is located behind the handrail 150. A guide 151 guides themesh inwardly. This acts to retain the middle part of the protectivescreen 46 in position. As the scaffold unit 10 is raised, the meshremains behind the handrail 150 but is stretched toward, as shown inFIG. 26.

In some embodiments, the lower end intermediate support frames 12, 14may be provided with an incorporated mid-rail and toeboard. FIGS. 27 and28 show these features. FIGS. 27 and 28 include an enlargement of detailW shown in FIG. 19. The mid-rail 152 and toeboard 154 can be seen inFIG. 28. The mid-rail 152 is supported by a number of generally verticalposts, one of which is shown at 156. The mid-rail and toeboard may beremovable from the scaffold unit.

FIG. 29 shows an enlarged view of detail AB shown in FIG. 13. This showsthe lower support platform 12 and the intermediate support platform 14in the lowered position. It will be appreciated that upper supportplatform 16, which can be partially seen in FIG. 29, will be directlyabove intermediate support platform 14. The support platform 12 supportsa deck 160. Similarly, support platform 14 supports a deck 162. Thedecks provide a support surface or walking surface on which workers andequipment can stand or walk. The linkage arrangements 35, 37 fold up andpartly fit into the space caused by the deck 160 acting as a spacerbetween the lower support frame 12 and intermediate support frame 14.Springs 164, 166 push against the lower support frame 12 in order tooperate and positively engage the locking mechanism, as will bedescribed in more detail with reference to FIGS. 42 and 44. Handrail 150also fits into this space, as can be more clearly seen in FIG. 30.Alternatively, one or more locking bars may be used to lock the scaffoldunit in the retracted position for transport and storage.

FIGS. 32 and 33 show expanded detail of how the legs of the scissorlinkages are pivoted together and how the handrail is mounted thereto.With reference to FIGS. 32 and 33, lower leg 170 is pivotally connectedto upper leg 172. Similarly, lower leg 174 is pivotally connected toupper leg 176. The lower are pivotally connected to each other at pivotpoint 178. Similarly, upper legs 172, 176 pivotally connected togetherat pivot point 180.

The legs 170, 172 are pivotally connected together by forming alignedholes in those links. A pin 182 extends through the holes and a lockingpin 184 is used to retain the pin 182 in position. It will be understoodthat the legs 170, 172 can pivot around pivot pin 182. Bushings, such asnylon bushings, bronze bushings or bushing are made from any othersuitable bushing material 186, may be inserted in the openings in thelegs in order to minimise friction and noise during pivoting. Thehandrail 150 may be positioned inside a bracket 188 that can bepivotally connected to pivot pin 182. In this regard, an opening 190 maybe formed in the head of pivot pin 182 and an appropriate fastening pin(not shown) may be used to connect the handrail bracket 188 to the pivotpin 182. The handrail 150 may be slidable within the bracket 188 toenable the brackets to slide along the handrail whilst the scaffold unitis being raised or lowered. In other embodiments, the handrail 150 islocked into position. Bracket 188 may swing open to enable easyinstallation and removal of handrail 150.

FIGS. 34 to 37 show operation of a horizontally extendable deck. Inparticular, lower support frame 12 is provided with a deck 160. Deck 160may have a horizontally extendable portion. As shown in FIG. 35, thehorizontally extending portion 200 can extend sideways from the deck160. FIG. 36 shows the extending portion 200 of deck 160 being furtherextended, with FIG. 37 showing the extending deck 200 being at itsmaximum horizontal extension. As can be seen, use of a horizontal deckhaving a portion that is both extendable and retractable can allow forthe deck to extend horizontally to fill in any gap or space between thescaffold unit 10 and a building that is adjacent to the raised scaffoldunit 10. In this manner, the scaffold unit 10 can be spaced from thebuilding at a desired minimum distance so that undesired contact betweenthe scaffold unit 10 and the building is avoided. This helps to avoidcausing damage to the building, particularly in instances where thescaffold unit 10 is being used adjacent to a completed building (forexample, for maintenance purposes or cleaning purposes).

Although not shown in FIGS. 34 to 37, the deck 160 will have a hollowhaving a side opening through which the extendable portion 200 of thedeck can be extended and retracted. The extendable portion 200 of thedeck may be extended and retracted using a drive means, such as a drivemotor. Alternatively, the extendable portion 200 of the deck may bemanually moved inwardly and outwardly. One or more locking arrangements,such as locking pins that fit into apertures in the deck 160 and theextendable portion 200 of the deck, may be used to lock the extendableportion of the deck in position.

The other support platforms may also be provided with decks that canextend and retract horizontally.

FIGS. 38 to 41 show a guard rail 18, 20 being moved from a lowerscaffold unit 10 to an upper scaffold unit 210. In FIG. 38, the lowerscaffold unit 10 is in its fully raised position. If it is desired toobtain access to even higher areas, a second scaffold unit 210 that isessentially identical to scaffold unit 10 is mounted to the uppersupport frame 16 of lower scaffold unit 10. As can be seen from FIG. 38,the guard rail 18 has a vertical support post 120. The lower end of thevertical support post 120 extends inwardly at 220 and then extendsvertically downwardly again at the very end, as shown at 222. In thisway, a major part of the length of support post 120 is spaced outwardlyfrom the upper support frame 16. This provides sufficient space toenable the upper scaffold unit 210 to be positioned on top of the uppersupport frame 16 of the lower scaffold unit 10 without first having toremove the guardrails 18 and 20.

Once the upper scaffold unit 210 has been placed on the lower scaffoldunit 10, the scaffold units 10, 210 may be locked together (as will bedescribed with reference to FIGS. 42 to 44). The guardrails 18, 20 maythen be unlocked (as described with reference to FIGS. 20 and 21) andrepositioned to be mounted into the appropriate support brackets mountedto the sides of the upper support frame of upper scaffold unit 210. Thisis shown in FIG. 40. The upper scaffold unit 210 may then be raised, asshown in FIG. 41. In FIG. 41, the upper scaffold unit 210 is partlyraised.

In order to lock the upper scaffold unit 210 to the lower scaffold unit10, an opening 230 that leads into a passage 232 that is formed in oneof the members of upper support frame 16 or in the corner castings ofthe upper support frame 16. The upper scaffold unit 210 includes a lowersupport frame 234, an intermediate support frame 236 and an uppersupport frame 238. Each of the support frames includes member cornercastings that have passages 240, 242 and 244. Passage 244 has an upperopening 246 of decreased diameter or size. Similarly, passage 244 has anupper opening 248 of decreased diameter or size. A biasing spring 250 ismounted in passage 240. Another biasing spring 252 is mounted in passage242. A locking bar 254 having a top cap 256 and a bottom cap 258 ispositioned so that it extends through aligned passages 240, 242, 244. Itwill be appreciated that the upper scaffold unit 210 shown in FIG. 42 isin the lowered position.

Once the upper scaffold unit 210 is positioned on the lower scaffoldunit 10, as shown in FIG. 42, the locking bar 254 is actuated byrotating by 90°. The top cap 256 and the bottom cap 258 have a narrowside and a longer side. Rotating the bar by 90° brings the narrow sideinto alignment with the narrow openings 230, 231 and 246. This enablesthe locking bar 254 to move downwardly such that bottom cap 258 passesthrough aligned narrow openings 230, 231, as shown in FIG. 43. This actsto lock the lower scaffold unit 10 to the upper scaffold unit 210. Itwill be appreciated that similar locking mechanisms are provided on eachcorner of the scaffold units. The upper scaffold unit may then beextended/raised, as shown in FIG. 44. In some embodiments, the lower endof the locking bar 254 may engage at its lower end with the lowerscaffold unit. For example, the lower end of the locking bar 254 may berestricted from moving further downwardly once it is moved into alocking position. In this embodiment, it may be possible to omit thesprings shown in FIGS. 42 to 44 and in FIG. 29.

FIGS. 45 to 47 show the connection of the legs of the scissor linkagesthat are pivotally connected at or near the corners of the supportframes. For example, in FIG. 45, leg 22 (refer to FIG. 6) and thecorresponding leg 270 on linkage 36 are interconnected by a rod 272. Rod272 is welded to respective scissor arms 22, 270. Rod 272 is a hollowrod that can receive an insert 274. This is shown in FIG. 46. Insert 274comprises a hollow locking insert 276 that is fitted with a threadedinsert 278. Bushes 280, such as nylon bushes, are fitted to an opening284 in scissor leg 22. The locking insert with fitted threaded insert278 is inserted into the hollow end of rod 272 prior to welding the rodto 72 to the scissor arms 22, 270. An appropriate threaded locking pinor locking bolt, such as pivot pin 99 or 101 (see FIG. 15) is thenpassed through the opening 284 and bushes 280, 282 to thereby pivotallyconnect the scissor arms 22, 270 to the lower frame members.

FIGS. 48 to 51 show various views of a base unit 300 in accordance withthe present invention. The base unit 300 comprises a frame made up offrame members 302, 304, 306 and 308 that are welded or bolted togetherto form a generally rectangular frame. Support surfaces 310, 312, 314are welded to the frame at locations at or near the corners of theframe. The frame may also be provided with corner castings, one of whichis numbered at 318, to assist in transport of the frame.

Each of the support surfaces 310, 312, 314, 316 is provided with anopening 350. Opening 350 can receive respective locking bars 254 (referto FIGS. 42 to 44) which allow the scaffold unit placed on the base unit300 to be securely fastened to the base unit in a manner that is similarto that as described with reference to FIGS. 42 to 44.

The frame is also provided with four leg assemblies, with each legassembly being located near a corner of the frame. One leg assembly isnumbered at 320 in FIG. 49. The leg assembly 320 includes a first leg322 and a second leg 324. Both legs 322, 324 can pivot about 90° fromthe retracted position shown in FIGS. 48 to 51 to an extended positionin which the legs extend generally vertically. Leg 322 is fitted with afoot 326. Similarly, leg 324 is fitted with a foot 328. The other legassemblies in the other corners of the frame are similar.

FIG. 55 shows more detail of the leg assembly 320. In FIG. 55, the leg322 has been pivoted to the extended position in which the leg 322extends in a generally vertical direction. Leg 324 is still in itsretracted position in which it is positioned in a generally horizontalorientation.

As can be seen from FIG. 55, leg 326 comprises an outer tube 330 havinga nut 332 welded position therein. An inner threaded rod 334 is mountedin a bearing block 336. The inner threaded rod 334 can rotate relativeto the outer tube 330. This causes the outer tube 330 to move along theinner threaded rod 334 to thereby adjust the length of the leg 322.

Returning to FIG. 49, leg 322 is pivotally mounted in bracket 340.Similarly, leg 324 is pivotally mounted in bracket 342. Leg 324 issomewhat shorter than leg 322.

FIG. 52 shows the longer legs 322 mounted at the end of the base unitnear frame member 308 being extended, whilst the legs at the other endof the base unit near frame member 304 remained retracted. In thisconfiguration, the end of the base unit at 304 can rest on the groundwhilst the feet of the long legs 322 at the end of the base unit near308 can also rest on the ground. This allows the base unit to bepositioned horizontally on sloping ground having a reasonable slope.

FIG. 53 shows the longer legs 322 at end 308 being extended and theshorter legs 324 at end 304 also being extended. This allows the baseunit to be horizontally set on gently sloping ground whilst alsoallowing the height of the base unit to be set at a desired level.

FIG. 54 shows an embodiment in which legs 322 mounted near frame member304 have been extended. This provides for the shorter legs at that endof the base unit to be extended whilst the other legs at the other endof the base unit remain retracted. This allows the other end of the baseunit to rest on the ground whilst the short extended legs at the endnear frame member 304 rest on the ground. In this configuration, thebase unit can be securely positioned on ground having a gentle slope.

It will be appreciated that the operator will select the legs to beextended (the shorter legs or the longer legs) and then adjust thoselegs to the desired height to ensure that the top of the base unit 300is level/horizontal and that it is at the correct height such that theextended scaffold unit placed on top will have its support decks at therequired height, for example at the required height necessary to alignthe support decks with floor levels of a building. FIGS. 56 to 59 showvarious views of a scaffold unit in accordance with another embodimentof the present invention. Referring initially to FIGS. 56 and 57, thescaffold unit 400 shown in these drawings includes a first supportplatform or support frame 402 and a second adjacent support platform404. It will be appreciated that further support platforms or supportframes may be mounted above frame 404 or below frame 402. Scissorlinkages 406, 408, which may be essentially identical to the scissorlinkages as described with reference to FIGS. 1 to 10, connect thesupport frame 402 to the support frame 404. In some embodiments, therewill be four scissor linkages connecting each support frame to anadjacent support frame. A drive mechanism similar to that shown in FIG.15 may be used to raise and lower the scissor linkages 406, 408.

In order to assist with the initial movement of the scaffold unit fromthe lowered position, further drive means in the form of initial liftdevices 410, 412 are positioned between frame 402 and frame 404. Theinitial lift devices can extend in an essentially vertical direction.For example, as shown in FIG. 56, when in the lowered position, theinitial lift devices 410, 412 have a short vertical extent. Whenextended, as shown in FIG. 57, the initial lift devices 410, 412 have amuch larger vertical extent. In order to move the scaffold unit 400 fromthe lowered position to the raised position, the initial lift devices410, 412 may be actuated to cause the support frame 404 to be raisedaway from the support frame 402. This, of course, also causes verticalextension of the scissor linkages 406, 408. The drive means to drive thescissor linkages may be actuated or may become more effective at raisingthe scissor linkages once the legs of the scissor linkages become morevertical, for example, once those legs are positioned at an angle ofgreater than 10° to the horizontal, to continue raising of the scaffoldunit.

The legs of the scissor linkages may extend at an angle of less than 10°to the horizontal when the scaffold unit 400 is in the lowered position.The initial lift devices 410, 412 may replace the biasing means 114,115, 116, 117 shown in the drive means of FIG. 15. Alternatively, theinitial lift devices 410, 412 may assist the biasing means shown in FIG.15 with the initial raising of the support frame.

In some embodiments, the support frame 404 may move away from the top ofthe initial lift devices 410, 412 as the support frame 404 moves to theraised position. In this regard, the initial lift devices 410, 412 mayhave a maximum vertical extension that is less than the distance betweenthe support frames 402, 404 in the fully raised position. It will beappreciated that the lower end of the initial lift devices 410, 412 maybe connected to the support frame 402 but the support frame 404 mightonly rest on the initial lift devices 410, 412 when in the loweredposition.

It will also be appreciated that FIGS. 57 and 59 show the scaffold unit400 in a partly raised position. When in the fully raised position, thelegs of the scissor linkages 406, 408, may extend at an angle of greaterthan 80° to horizontal.

FIGS. 60 to 63 show a scaffold unit 420 in accordance with anotherembodiment of the present invention. The scaffold unit 420 comprises asupport frame 422 and an adjacent support frame 424. Although not shownin FIGS. 60 to 63, it will be appreciated that further support framesmay be included in the scaffold unit 420. In one embodiment, thescaffold 420 may include 3 support frames. The support frame 422includes a side beam that has a plurality of spaced openings, some ofwhich are numbered at 426, 428, 430, 432, 434.

Scissor linkages 436, 438 connect support frame 422 to support frame424. The scissor linkages 436, 438 may be similar to the scissorlinkages as described with reference to the embodiment shown in FIGS. 1to 10. In particular, scissor linkage 436 includes a leg 440 that ispivotally connected at its lower end to the support frame 422. Scissorlinkage 436 also includes a leg 442 that is pivotally connected at itsupper end to support frame 424. Scissor linkage 436 has a leg 444 thathas a lower end that is movable inwardly and outwardly along a track orguide of the support frame 422. Scissor linkage 436 also includes a leg446 that has an upper end that is movable inwardly and outwardly along atrack or guide of the support frame 424.

In the embodiment shown in FIGS. 60 to 63, the location of the scissorlinkages 436, 438 are adjustable and can be moved to a desired location,depending on the site requirements. In order to connect the scissorlinkage 436 to support platforms 422, 424, openings in the respectiveends of legs 440, 442 are aligned with respective openings formed in theside beams of support frames 422, 424. Pivot pins 448, 450 are theninserted through the aligned openings to thereby pivotally connect therespective ends of legs 440, 442 to the respective support frames 422,424. The inwardly/outwardly movable ends of legs 444, 446 can slidealong their respective guides or tracks during repositioning of thescissor linkages inwardly or outwardly. The drive mechanism that drivesthe scissor linkages to raise and lower the scissor linkages may bedisconnected during this repositioning process.

In FIG. 60, the scissor linkage 436 is shown to be pivotally connectedto opening 430. Scissor linkage 438 is similarly positioned at the otherend of the scaffold unit 420. In FIG. 61, the scissor linkage 436 ispivotally connected to opening 428. Scissor linkage 438 is similarlypositioned at the other end of the scaffold unit 420. In FIG. 62, thescissor linkage 436 is pivotally connected to opening 426. Scissorlinkage 438 is positioned such that it is pivotally connected at opening452. As can be seen from FIG. 62, scissor linkage 436 is positioned atan outer end of the scaffold unit 420 whereas scissor linkage 438 ispositioned inwardly from an outer end of the scaffold unit 420. In FIG.63, scissor linkage 436 is pivotally connected to opening 430 andscissor linkage 438 is pivotally connected to opening 452. Thus, theposition of the respective scissor linkages can be moved and located inaccordance with specific site requirements for any particular job.

FIGS. 64 and 65 show side views of a scaffold unit 470 in accordancewith another embodiment of the present invention. The scaffold unit 470includes support frame 472 and support frame 474. Scissor linkages, 476,478 connect support frames 472, 474. In contrast to the embodiment shownin FIGS. 1 to 10, the scissor linkages are not located directly undercorners of the support platforms. Rather, they are mounted slightlyinboard from the corners. Further, the fixed pivot points of the scissorlinkages are located at the inner part of the scissor linkages. Forexample, the fixed pivot points of scissor linkage 476 are shown at 480,482 and the fixed pivot connections of scissor linkage 478 are shown at484, 486. Appropriate changes to the drive mechanism shown in FIG. 15can be made so that the inwardly and outwardly movable ends of thescissor linkages are raised by moving those ends inwardly and lowered bymoving those ends outwardly.

FIGS. 66 and 67 show a scaffold unit 500 having support frames 502, 504.Vertical telescoping members 506, 508 extend between the support frames502, 504. The vertical telescoping members 506, 508 are suitablyconnected at either end to the respective support frames 502, 504. Thevertical telescoping members 506, 508 may comprise hydraulic cylindersor hydraulic rams, pneumatic cylinders or pneumatic rams, or columnlifters. In this embodiment, motive power, such as a source ofpressurised hydraulic fluid or pressurised pneumatic fluid, or anelectric actuator, may be mounted on the scaffold unit 500.Alternatively, the scaffold unit 500 may be connected to externalsources of pressurised fluid or electrical power. The verticaltelescoping members 506, 508 may be operated such that they extend tothereby raise the scaffold unit 500 and retract to thereby lower thescaffold unit 500.

FIGS. 68 and 69 show side views of one end of a scaffolding unit inaccordance with another embodiment of the present invention. Theembodiment shown in FIGS. 68 and 69 includes three support platforms602, 604, 606 that are interconnected by scissor linkages, some of whichare shown at 608, 610. The scaffold unit 600 different is from thatshown in embodiments in that a gas strut 612 is mounted at 614 to partof the upper support platform. The gas strut 612 extends downwardly in agenerally vertical direction. The gas strut 612 comprises a two-stagegas strut. A lower and 616 of the gas strut 612 is provided with anabutment 618 that rests on an abutment surface 620 that is mounted to alowered chassis member 622 of the scaffold unit when the scaffold unit600 is in a retracted condition. This is best shown in FIG. 68. When thescaffold unit is in the retracted condition, the two-stage gas/612 isfully compressed.

FIG. 69 shows the scaffold unit 600 in a partly extended condition. Ascan be seen, as the drive units starts to extend the scaffold unit fromthe retracted condition, the gas strut 612 applies an upwardly directedbiasing force to the upper platform 606. This assists the drive unit ininitially moving the scaffold unit out of the fully retracted condition.As can be seen in FIG. 69, as the scaffold unit continues to extend, thegas strut 612 also extends so that the intermediate portion 624 and thelower portion 626 of the gas strut 612 become fully extended. When thegas strut 612 is fully extended, the scaffold unit 600 has been extendedto a position that is sufficiently high such that the drive unit cancontinue to extend and raise the scaffold unit without assistance of thegas strut. As shown in FIG. 69, as the scaffold unit 600 continues toextend, the abutment member 618 moves upwardly and away from theabutment surface 620. When the scaffold unit 600 is moved to an extendedposition to the retracted position, the abutment member again comes intocontact with the abutment surface 620 and the gas strut 612 become iscompressed as the scaffold unit continues to retract.

In the embodiment shown in FIGS. 68 and 69, gas struts may be mounted ator near each corner of the upper platform. Alternatively, a smallernumber of gas struts may be used.

In the embodiment shown in FIGS. 68 and 69, it may be possible to omitthe biasing blocks 114 to 117 shown in FIG. 15. FIG. 70 shows analternative drive arrangement to that shown in FIG. 15. In FIG. 70, thebulk of the drive arrangement is simply that shown in FIG. 15 and forconvenience and brevity of discussion, similar features need not bedescribed further.

As can be seen from FIG. 70, the biasing means 114, 115, 116 and 117shown in FIG. 15 have been omitted. In this regard, the gas strut 612may functionally replace those biasing means. Further, in the embodimentshown in FIG. 70, gearbox 650 has an input shaft 652 that can acceptdrive from a removable electric motor. Therefore, rather than having theelectric motor mounted to the scaffolding unit (which may require thateach platform be provided with an electric motor), a single electricmotor that is connectable to the driveshaft and removable from thedriveshaft 652 may be used to separately raise each platform. In anotheralternative embodiment, the driveshaft 652 may include or be replaced bya 90 degree gearbox which will allow the motor to be removed in avertical direction

The drive arrangement shown in FIG. 70 also includes a T gearbox 654that drives a ball screw 656 that extends through respective ball nuts658, 660. The respective ends of the ball screw 656 are mounted forrotation with in transverse shafts 662, 664.

FIG. 71 shows a perspective view of the scaffold unit 600 in theextended position. The scaffold unit 600 includes four gas struts thatare connected in vertically extend from the upper deck 606. Three ofthese are shown at 612, with the fourth one being in FIG. 71. A handrail 670 can also be seen. Like other embodiments, the hand rail 670 ismounted to the pivot points between one of the scissor leg is. However,handrail 670 may remain connected to the legs during storage, as isshown in FIG. 73.

As shown in FIG. 72, the central part of the scissor linkage 673 shownin FIG. 71 includes a lower leg 674 that is pivotally connected by apivot pin 676 to upper leg 678. The scissor linkage also includes anupper leg 680 that is pivotally connected to a lower leg 682. Thepivotal connection is made by providing a pin 684 having an internalthread extending through respective openings in or near the ends of thelegs 680, 682 (one of the openings is shown at 685). A locking washer686 and a lock nut 687 are used to hold the pivot pin 684 in place. Thelocking washer 686 has an internal projection 688 that rest inside keyway 689 of the pivot pin 684 to thereby fix the locking washer 686 inposition relative to the pin 684.

The scaffold unit of the present invention provides a scaffold unit thatis very compact when in the lowered position, thereby enabling easytransport and storage. The scaffold unit may be raised to its raisedposition to provide one or more raised support platforms to enableworkers to work on higher levels of the building. Further scaffold unitsmay be mounted on top of the scaffold unit if greater height isrequired. A number of units may be mounted next to each other so thatscaffolding extending along a side of a building can be obtained.Erection of the scaffold unit beside a building is much quicker and lesslabour-intensive than erection of conventional scaffolding. In someembodiments, the scaffold unit has linkages at each corner of thesupport frames, thereby providing increased strength and stability.

In embodiments where the scaffold unit has scissor linkages at eachcorner and the scissor linkages extend at an angle of greater than 80°when in the erected position, when the unit is fully erected the scissorlinkages provide minimal interference to access to the building or aworksite located adjacent to the work platform. In this regard, as thescissor linkages are located at the corners and are extending in anysensually vertical direction, the scissor linkages do not extend to anygreat lateral extent, thereby providing clear space along the bulk ofthe length of the work platform. Thus, the scissor linkages do notsubstantially get in the way. Further, if two or more scaffold units areplaced end-to-end, a relatively unhindered walkway between adjacentunits can be formed.

Significant other advantages also arise from the present invention, whencompared to conventional scaffolding units. In particular, the presentinvention is likely to greatly reduce or even eliminate accidents andinjuries due to manual handling, falling objects and fall from heightsduring erection and dismantling. The labour force required to installthe scaffolding is greatly reduced when compared to conventionalscaffolding. Indeed, it is envisaged that only 2 installers will berequired to install and erect the scaffold unit of the present inventionat a worksite. Erection of conventional scaffolding can often require asignificantly larger workforce. The installation time required toinstall the scaffold unit to its working height is also greatly reduced,when compared to conventional scaffolding. It will be appreciated thatthe requirement for a smaller number of workers to erect the scaffoldunit and a more rapid installation time means that the scaffold unit ofthe present invention can be installed at significantly reduced costswhen compared to conventional scaffolding. A further advantage arises inthat installation costs of scaffold units of the present invention canbe quite accurately estimated, thereby providing more certainty inpreparing cost estimates and reducing the time and costs associated withtendering for projects.

The scaffold unit of the present invention is provided essentially as afully assembled product from the factory (with only a small or minimalnumber of removable or attachable elements). This reduces the number ofloose components and also reduces or minimises the likelihood ofcomponents going missing. Further, the worksite can be much tidier andthere is reduced or no need for storage of components on-site. This alsoreduces storage costs and transport costs when compared to conventionalscaffolding. Further, smaller storage facilities may be used. As afurther benefit, it is believed that the scaffold unit of the presentinvention should be able to be certified at the factory where it isassembled, thereby reducing certification costs on site.

In some embodiments, the scaffold unit of the present invention has acontainment screen fixed to the scaffold unit. Therefore, as thescaffold unit is erected, the containment screen automatically extendsand is in place without requiring additional installation. In someembodiments, the height of the work platforms can be closely and easilycontrolled.

In the present specification and claims (if any), the word ‘comprising’and its derivatives including ‘comprises’ and ‘comprise’ include each ofthe stated integers but does not exclude the inclusion of one or morefurther integers.

Reference throughout this specification to ‘one embodiment’ or ‘anembodiment’ means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more combinations.

In compliance with the statute, the invention has been described inlanguage more or less specific to structural or methodical features. Itis to be understood that the invention is not limited to specificfeatures shown or described since the means herein described comprisespreferred forms of putting the invention into effect. The invention is,therefore, claimed in any of its forms or modifications within theproper scope of the appended claims (if any) appropriately interpretedby those skilled in the art.

1. A scaffold unit comprising at least two support platforms or twosupport frames, at least one of the support platforms or support framesbeing movable between a lowered position and a raised position, aplurality of scissor linkages linking one support platform or supportframe with a next support platform or support frame, each of the scissorlinkages including a plurality of legs, each scissor linkage having aleg pivotally connected to or near a corner of one of the supportplatforms or support frames and a leg pivotally connected to or near acorner of a next support platform support frame, wherein a leg ispivotally connected at or near each corner of a support platform orsupport frame.
 2. A scaffold unit as claimed in claim 1 wherein thescissor linkages comprise a first leg and a second leg, with the firstleg being pivotally connected to a lower support platform or supportframe at or near a corner of the lower support platform or supportframe, the first leg and second leg being pivotally connected to eachother at an approximate midpoint thereof, the second leg having a lowerend that is reciprocally movable relative to the lower support platformor support frame, the first leg having an upper end that is reciprocallymovable relative to an upper support platform or support frame, thesecond leg having an upper end that is pivotally connected to the uppersupport platform or support frame at or near a corner of the uppersupport platform or support frame.
 3. A scaffold unit as claimed inclaim 1 wherein the scissor linkages comprise a first leg and a secondleg, with the first leg being pivotally connected to a lower supportplatform or support frame at or near a corner of the lower supportplatform or support frame, the first leg and the second leg beingpivotally connected to each other at an approximate midpoint thereof,the second leg having a lower end that is reciprocally movable relativeto the lower support platform or support frame, a third leg having anupper end that is pivotally connected to an upper support platform orsupport frame at or near a corner of the upper support platform orsupport frame, a fourth leg having an upper end that is reciprocallymovable relative to the upper support platform or support frame, thethird leg and the fourth leg being pivotally connected to each other atan approximate midpoint thereof, the third leg having a lower end thatis pivotally connected to an upper end of the first leg and the fourthleg having a lower end that is pivotally connected to an upper end ofthe second leg.
 4. A scaffold unit as claimed in any one of thepreceding claims wherein the pivotal connection points of the respectivelegs to one of the platforms or support frames are located outwardly ofthe sliding ends of the other legs of each scissor linkage.
 5. Ascaffold unit as claimed in any one of claims 1 to 3 wherein the slidingends of the respective scissor linkages are located outwardly of thepivotal connection points of the other ends of each scissor linkage. 6.A scaffold unit as claimed in any one of the preceding claims whereineach support platform or support frame has 4 scissor linkages attachedto a lower side thereof.
 7. A scaffold unit as claimed in any one of thepreceding claims further comprising a drive means for raising andlowering at least one of the support platforms or support frames betweenthe lowered position and the raised position.
 8. A scaffold unit asclaimed in claim 7 wherein the drive means is mounted to the scaffoldunit.
 9. A scaffold unit as claimed in any one of the preceding claimswherein legs of the scissor linkages extend at an angle of less than 8°to horizontal when the scaffold unit is in the lowered position, or legsof the scissor linkages extend at an angle of from 3° to 7° to thehorizontal when the scaffold unit is in the lowered position, or legs ofthe scissor linkages extend at an angle of from 4° to 6 to thehorizontal, when the scaffold unit is in the lowered position. °, orlegs of the scissor linkages extend at an angle of from about 4° to 5°to the horizontal when the scaffold unit is in the lowered position. 10.A scaffold unit as claimed in any one of the preceding claims whereinthe scaffold unit further comprises a further drive means or a biasingmeans to facilitate initial movement of a support platform or supportframe from a lowered position.
 11. A scaffold unit as claimed in claim10 wherein the further drive means is selected from one or more of acolumn lifter, a hydraulic ram, an air bag, or a pneumatic cylinder andthe biasing means is selected from one or more springs, or one or moreresilient members, or one or more elastomeric or rubber members, or oneor more elastomeric or rubber blocks, or one or more struts, or one ormore gas struts.
 12. A scaffold unit as claimed in claim 10 or claim 11wherein the biasing means provides a biasing force to the legs or to oneof the support platforms or support frames when the scaffold unit is inthe lowered position, the biasing force acting in a direction to assistraising the scaffold unit.
 13. A scaffold unit as claimed in any one ofclaims 10 to 12 wherein the biasing means extend in a verticaldirection.
 14. A scaffold unit as claimed in any one of the precedingclaims wherein the legs extend at an angle of greater than 80°, orgreater than 85°, to the horizontal when the scaffold unit is in theraised position.
 15. A scaffold unit as claimed in any one of thepreceding claims wherein the legs extend at an angle of about 86.5° tothe horizontal when in the raised position.
 16. A scaffold unit asclaimed in claim 2 or 3 or as claimed in any one of claims 4 to 15 whenappended to claim 2 or claim 3 wherein the legs that are reciprocallymovable relative to one of the support platforms or support frames areconnected to one or more rollers that can move along a track or guide inor mounted to the support platform or support frame.
 17. A scaffold unitas claimed in claim 7 or in any one of claims 8 to 16 when appended toclaim 1 wherein the drive means comprises a drive motor or an electricmotor.
 18. A scaffold unit as claimed in claim 17 wherein the drivemotor or the electric motor causes a drive bar or drive member toreciprocally move relative to one of the support platforms or supportframes, movement of the drive bar or drive member causing the legs tomove.
 19. A scaffold unit as claimed in claim 17 or claim 18 wherein thedrive bar or drive member causes at least some of the legs that aremounted for reciprocal movement relative to one of the support platformsor support frames to move relative to the support platform or supportframe.
 20. A scaffold unit as claimed in any one of claims 17 to 19wherein the drive motor causes a ball screw or a worm gear to rotate,the ball screw or worm gear extending through a nut fixedly mounted to adrive bar or drive member, wherein rotation of the ball screw or wormgear causes the drive bar or drive member to move laterally outwardly orlaterally inwardly.
 21. A scaffold unit as claimed in claim 21 whereinthe drive motor passes drive through a gear arrangement to causerotation of the ball screw or worm gear.
 22. A scaffold unit as claimedin any one of the preceding claims wherein the scaffold unit is also beprovided with a braking means that can be selectively actuated toprevent raising or lowering of the scaffold unit and selectively turnedoff or disengaged to allow raising or lowering of the scaffold unit. 23.A scaffold unit as claimed in claim 22 wherein the braking means engageswith one or more components of the drive means.
 24. A scaffold unit asclaimed in any one of the preceding claims wherein the scissor linkagesmay be moved and repositioned inwardly or outwardly relative to thesupport frame or support platform.
 25. A scaffold unit as claimed inclaim 24 wherein the support frame or support platform is provided witha plurality of spaced openings, one leg of a scissor linkage having anopening that can be brought into alignment with one of the plurality ofspaced openings and a connecting pin passed through the aligned openingsto thereby pivotally connect the one leg of the scissor linkage to thesupport platform or support frame, another leg of the scissor linkagethat is associated with that support platform or support frame beingmovable along the support platform or support frame to allowrepositioning of the scissor linkage.
 26. A scaffold unit as claimed inany one of the preceding claims wherein at least one of the supportplatforms or support frames is provided with a support surface on whicha worker can stand, the support surface including a horizontal extensionmovable between a retracted position and an extended position, thehorizontal extension extending outwardly from the support platform orsupport frame when extended.
 27. A scaffold unit as claimed in claim 26wherein the horizontal extension extends along a length of the supportplatform or support frame.
 28. A scaffold unit as claimed in any one ofthe preceding claims wherein the scaffold unit is provided with aprotective screen on one side thereof.
 29. A scaffold unit as claimedclaim 28 wherein the protective screen automatically extends when thescaffold unit is raised.
 30. A scaffold unit as claimed in any one ofthe preceding claims wherein the scaffold unit is provided with one ormore handrails.
 31. A scaffold unit as claimed in any one of thepreceding claims wherein an uppermost support platform or support frameis provided with one or more handrails or guardrails that are removablymounted to a scaffold unit.
 32. A scaffold unit as claimed in any one ofthe preceding claims wherein the support platform or support frame has asupport surface that enables a worker to stand or walk thereon.
 33. Ascaffold unit as claimed in any one of the preceding claims wherein thescaffold unit is provided with one or more stays extending between onesupport platform or support frame and a next support platform or supportframe.
 34. A scaffold unit as claimed in claim 33 wherein the one ormore stays extend diagonally between the support platforms or supportframes.
 35. A scaffold unit as claimed in claim 33 or claim 34 whereinthe one or more stays are extendable stays.
 36. A scaffold unit asclaimed in claim 35 wherein the one or more stays include self lockingmeans to lock the stays into an extended position when the scaffold unitis moved to the raised position.
 37. A scaffold unit as claimed in anyone of the preceding claims wherein the scaffold unit is provided withlocking means for locking a first scaffold unit to a second scaffoldunit positioned on top of the first scaffold unit.
 38. A scaffold unitas claimed in claim 37 wherein the locking means comprises a locking barextending through apertures located in the first scaffold unit and thesecond scaffold unit.
 39. A scaffold unit as claimed in any one of thepreceding claims further comprising a base unit, the base unitcomprising a frame having one or more support surfaces on which thescaffold unit may be supported, the frame including a plurality of legsmovable between a retracted position and an outward position, theplurality of legs comprising adjustable legs.
 40. A scaffold unit asclaimed in any one of claims 1 to 38 wherein the scaffold unit isprovided with adjustable legs or adjustable feet that extend below thelower support platform or support frame in use.
 41. A scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, a plurality of scissorlinkages linking one support platform or support frame with a nextsupport platform or support frame, each of the scissor linkagesincluding a plurality of legs, wherein the legs of the scissor linkagesextend at an angle of at least 80° to horizontal when the scaffold unitis in the raised position. In some embodiments, the scaffold unit has atleast 4 sets of scissor linkages linking one support platform or supportframe for next support platform or support frame.
 42. A scaffold unitcomprising at least two support platforms or two support frames, atleast one of the support platforms or support frames being movablebetween a lowered position and a raised position, a plurality of legsextending between one support platform or support frame and a nextsupport platform or support frame, at least some of the legs having apivotal connection to the support platform or support frame, the legsbeing movable during movement of the scaffold unit from the loweredposition to the raised position and vice versa, the legs extending at anangle of less then 10° to horizontal when the scaffold unit is in thelowered position.
 43. A scaffold unit comprising at least two supportplatforms or two support frames, at least one of the support platformsor support frames being movable between a lowered position and a raisedposition, a plurality of legs extending between one support platform orsupport frame and a next support platform or support frame, at leastsome of the legs having a pivotal connection to the support platform orsupport frame, the legs being movable during movement of the scaffoldunit from the lowered position to the raised position and vice versa,wherein a position of the pivotal connection between a leg and thesupport platform or support frame can be moved between a plurality ofpositions.
 44. A scaffold unit as claimed in any one of the precedingclaims further comprising one or more of access stairs for providingallow access between support platforms or support frames on differentlevels, one or more rubbish chutes or one or more loading bays.
 45. Ascaffold unit as claimed in any one of the preceding claims furthercomprising a locking means to lock the scaffold unit in the loweredposition.
 46. A scaffold unit as claimed in any one of the precedingclaims wherein substantially clear access to a work site is providedalong a substantial length of the platform or support frame when thescaffold unit is in the extended configuration.